Discusses the development, workings, and research on piezo motors. Also called ultrasonic motors or vibration motors, piezo motors move by a wave produced by a piezoelectric crystal. (MVL)

Addresses the relationship between car speed and the safe distance between cars in a linear flow of traffic. (WRM)

Presents an activity in which students work in cooperative groups and roll balls down inclined planes, collect data with the help of an electronic motion detector, and represent data with a graphing calculator to explore concepts such as mass, gravity, velocity, and acceleration. (Contains 12 references.) (Author/ASK)

This paper analyses the design parameters for an absorber used for removal of toxic acid gas (in particular sulfur dioxide) from a process gas stream for environmental health protection purposes. Starting from the equilibrium data, Henry's law constant was determined from the slope of the y-x diagram. Based on mass balances across the absorber,…

The idea of teaching physics to ninth-graders, known as "Physics First," has become more and more popular among physics educators in this country. However, introducing ninth-grade physics has been an uphill battle; such a change has a major impact on the students, parents, teachers, and the school administration. Switching to Physics First affects…

Incandescent lamps with tungsten filaments have been in use for about a century while being gradually replaced by fluorescent lamps; in another generation both will quite probably be largely replaced by light-emitting diodes. Incandescent lamps (simply called "lamps" in what follows) burn out after a lifetime that depends mostly on the temperature…

Energy is a critical concept in physics problem-solving but is often a major source of confusion for students if the presentation is not carefully crafted by the instructor or the textbook. The first article in this series discussed student confusion generated by traditional treatments of work. In any discussion of work, it is important to state…

It's a situation every avid cyclist knows only too well. If you cycle up a hill and then back down with no net change in elevation, it seems as if your slower uphill speed and faster downhill speed should offset each other. But they don't. Your average speed is less than it would have been had you cycled the same distance on a level road.…

Despite reports to the contrary, the availability of physics as a course for high school students is not equitably distributed throughout the United States. While some schools provide physics for all who wish to take it, a more common scenario is limited availability, often open only to the few students who have completed the necessary…

Many high school and introductory college physics instructors ponder the choice between "open text" exams versus "facts and formulae sheet" exams. Other alternatives are closed book/closed notes exams or an instructor-prepared sheet of facts and relevant formulas. There is no agreement on merit. Rehfuss strongly opposes allowing students to use…

Ballistocardiograms (BCGs) are graphical representations of the recoil from the pumping action of the heart. Introductory mechanics and a basic knowledge of the circulatory system are sufficient to understand the key features of a BCG. BCGs with adequate detail for instructional purposes may be produced easily and rapidly using hardware (a force…

A number of well-known hydrostatics problems dealing with Archimedes' principle concern a loaded boat floating in a pool. Examples of this sort of problem include: 1. (a) If a stone is thrown overboard from a boat floating in a pool, does the water level in the pool rise, fall, or remain unchanged? (b) If a hole is made in the bottom of the boat…

Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity. The problem was first investigated by Einstein in his famous 1905 paper by using the Lorentz transformations to switch from the mirror's rest frame to the frame where the mirror moves at a…

Doing physics "magic shows" for the general public or for local area schools is usually an integral part of any physics department's outreach program. These demonstration shows should not only teach fundamental physics principles with "standard" demonstrations (like the rocket cart) but should also include the "wow!" types of demonstrations for…

Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to…